The Sea Launch Commander and Odyssey launch platform in the Pacific Ocean during tests last year. Photo: William Hartenstein

The Sea Launch venture experienced the agony of defeat on Sunday when its Zenit rocket veered off course and crashed into the Pacific Ocean, destroying the first ICO mobile communications satellite.

The failure is a major setback for the international Sea Launch consortium and its partners in the U.S., Ukraine, Russia and Norway. Sea Launch had achieved success with its first two flights last year.

The ill-fated mission began when the three-stage Zenit 3SL rocket roared to life in the predawn darkness atop the Odyssey launch platform -- a converted oil-drilling rig -- positioned along the equator in the Pacific Ocean. Liftoff occurred within a tight one-second window at 1449 GMT (9:49 a.m. EST).

All appeared to be proceeding normally as the Ukrainian- and Russian-made rocket streaked southeastward from the launch site located at 154 degrees West longitude, or 1,400 miles south of Hawaii. The Zenit's first stage is believed to have operated normally and the protective nose cone enclosing the satellite payload was released.

About 2 1/2 minutes after launch, the Zenit's second stage ignited and soon after the trouble started.

Launch officials aboard the Sea Launch Commander ship reported intermittent dropouts in data signals coming from the rocket. Sea Launch was using NASA's orbiting Tracking and Data Relay Satellite System, or TDRSS, to receive data from the rocket.

Initially, the data loss was not seen as a major concern but the problem continued with the rocket's upper stage -- the Russian-built Block DM-SL -- when it apparently ignited about nine minutes into the flight.

What information was available showed the rocket was losing altitude and not gaining enough speed to make it into space. The data was the last communications received from the rocket.

"During the third stage burn, we got what we think was some indication of an off-nominal trajectory for the spacecraft," Sea Launch president Wilbur Trafton announced about two hours after liftoff.

What caused the rocket to malfunction is not yet known.

The Zenit 3SL rocket lifts off during the first commercial launch last October. Photo: Sea Launch

The Block DM-SL third stage was supposed to boost the attached ICO spacecraft into a preliminary orbit around Earth. The upper stage firing, scheduled to last about eight minutes, was required to achieve a safe orbit. How long the firing actually lasted was not released by Sea Launch on Sunday.

After completing the planned upper stage burn at T+plus 17 minutes, the rocket would have coasted through space for more than 90 minutes before the Block DM-SL reignited to inject the Hughes-built ICO satellite into a Medium-Earth-Orbit about 6,500 miles high.

During the coast period, however, a stream of live data from the rocket was not planned. The next communications session with the ground was expected through a Russian tracking station just over an hour after liftoff.

Engineers anxiously waited to hear from the rocket, thinking it arrived in orbit, but there was only silence.

Hopelessly off course, the rocket had already plunged back to Earth and crashed into the Pacific Ocean about 2,700 miles (4,300 km) downrange from the Odyssey launch platform.

The incident posed no known safety threat to any populated areas, officials said.

The Sea Launch partners will begin separate probes into the mishap. Ukraine's Yuzhnoye/Yuzhmash built the first two stages and Russia's Energia provided the Block DM-SL. Boeing made the nose cone. Once the U.S. government approves a Technical Assistance Agreement, an investigation oversight board will be formed.

"I can only express sincere regret to Hughes and ICO for this event," Trafton said. "We got a good rocket and we got a great team. As someone once said, this business is not for the faint of heart. So these things do happen."

"This is a huge setback emotionally," said Amy Buhrig, Sea Launch vice president for marketing. "But the partners are technically brilliant people and we will get back to business."

Sea Launch had hoped for three or four more missions this year including PanAmSat's PAS-9 the United Arab Emirates' Thuraya geomobile communications satellites and spacecraft for XM Satellite Radio.

"We will find out what happened and we'll recover and we'll keep launching satellites," Trafton said.

An artist's concept of an ICO satellite orbiting Earth. Photo: Hughes Space and Communications

For the London-based ICO Global Communications, the failure was a rough start to its satellite deployment campaign. ICO planned to launch 12 satellites -- 10 primary and two spares -- to provide its commercial cellular telephone and data relay services beginning in October 2002.

"We are disappointed with the loss of our first satellite. But launch failures are a well-known risk in this industry and ICO's planning has, from the outset, taken into account the possibility of such an occurrence," said Richard Greco, ICO's chief executive officer.

"We have mitigated the impact of such a failure by building and planning to launch 12 satellites even though our intended service requires only 10 operational satellites in orbit."

The Hughes-built satellite lost in the accident, reportedly valued at $100 million, was slated to undergo a six-month testing session before the next ICO craft was launched. The tests were aimed at verifying the satellite design and ICO ground network, the company said.

When another ICO satellite might be launched has not been determined, said spokesman Joe Tedino.

The future launches are booked aboard five Boeing Delta 3, four Russian Proton and two Lockheed Martin Atlas 2AS rockets. Boeing has reserved May 31 as a launch date for its first ICO launch from Cape Canaveral Air Force Station, Florida.

Greco said Sunday's launch was "adequately insured to cover the anticipated costs of building and launching a replacement spacecraft." The arrangement did not include a replacement Zenit launch.

ICO has been mired in bankruptcy proceedings since last summer. The company was saved by investor Craig McCaw and its serves revamped with an emphasis on global data transmissions and Internet connectivity through the ICO satellite constellation.

The ICO system uses enhanced versions of Hughes' HS 601 satellite platform, weighing just over 6,000 pounds at launch. The 10 primary satellites will orbit into groups of five in two orthogonal planes, each inclined at 45 degrees to the equator. That will allow complete, overlapping coverage of the Earth.